Accountable Care Organizations (ACOs) are being pursued by the Centers for Medicare and Medicaid Services (CMS) as a means to rein in health care cost growth while improving quality of care, but little is known about how ACO efforts to improve health care efficiency might affect health care equity. In this context, the candidate (Dr. Valerie A. Lewis) seeks to understand how ACOs affect racial and socioeconomic disparities in health care outcomes. The candidate, a sociologist and health services researcher at the Geisel School of Medicine at Dartmouth, will leverage this application to develop her research agenda and develop into an independent investigator. During the period of support, she will pursue didactic instruction in several disciplines, including training in clinical conditions and organizational behavior along with leadership development. She will also have ample opportunity for mentored, project-based learning, including developing advanced understanding of how to measure quality of care. The proposed research plan has three aims: Aim 1. To examine Medicare ACO coverage across patient race and socioeconomic status. Dr. Lewis will use Medicare claims data to examine whether disadvantaged patients are more or less likely than other patients to receive care from ACO providers compared to non-ACO providers and will examine the relative effects of (a) patterns of provider participation in ACOs and (b) patient selection. She will then use the National Survey of ACOs to determine if disadvantaged ACO patients are cared for at ACOs that are systematically different from other ACOs (e.g., types of ACO providers or services, ACO capabilities). Aim 2. To examine how Medicare ACO programs impact disparities in patient care outcomes. Dr. Lewis will use longitudinal Medicare claims data to examine how Medicare ACO programs affect disparities in quality outcomes over time. Analysis will focus on the extent to which changes in disparities are a result of differences withi providers (e.g., all ACO providers improve care for disadvantaged groups) or across providers (e.g., providers serving disadvantaged patients make rapid improvements under ACO programs). Aim 3. To understand how organizational characteristics, capabilities, and strategies influence changing disparities over time under Medicare ACO programs. Dr. Lewis will examine how and why organizational characteristics and capabilities influence changing disparities under ACO models. She will use data from the National Survey of ACOs to explore how ACOs' organizational characteristics (e.g., partnership structure, governance, capabilities) and implementation strategy (e.g., care management programs, physician feedback mechanisms) affect changes in disparities over time. Finally, she will follow up with in-depth interviews to understand how organizational characteristics may be detrimental or beneficial to changing disparities in care. Findings from this project will inform policymakers and implementers about how the ACO model can best facilitate improved health care equity alongside important goals of increased efficiency.